An assessment of indoor air quality in two contrasting buildings in London

• Main Authors: Mohd Aris, Mohd Shukri, Barratt, Benjamin, Kelly, Frank
• Format: Conference or Workshop Item
• Language: English
• Published: 2011
• Subjects: QH301 Biology; RA1190 Toxicology
• Online Access: http://irep.iium.edu.my/40840/5/40840-new.pdf; http://irep.iium.edu.my/40840/

Background: People spend most of their time indoors in buildings such as schools and offices as well as their homes. Over recent years there has been increased interest in Indoor Air Quality (IAQ) suggesting that the contribution of outdoor pollutant penetration and indoor airborne particulate and gaseous pollutants may be responsible for the aggregation of a number of respiratory illnesses. Because of these possible health implications it is important to understand the characteristics of each air pollutant inside/outside (I/O) the building and the variables affecting the degree of exposure. The findings from this study will be used to establish a London Indoor Air Quality Network to compliment the existing outdoor network. Objectives: Long term monitoring of particulate matter (PM) and gaseous pollutant (NOx & O3) inside and outside two different buildings was undertaken. The sites represent two extreme building conditions – one which is a mechanically ventilated office building adjacent to a busy road and the second, a naturally ventilated school building located in a London suburb. Building occupancy, ventilation details and indoor activity diaries were recorded to help interpret gaseous and particulate pollutant characteristics and sources. Methodology: Indoor and outdoor gaseous pollutants were monitored by continuous Oxides of Nitrogen (NOx)and Ozone (O3) analysers; Particle mass concentration was simultaneously monitored using Dust OSIRIS Instruments. These data were remotely accessed via in-house database software. Exposed microfibre glass filters were collected routinely for further particulate oxidative potential analysis. Results: At the mechanically ventilated office building (roadside), diurnal variation of indoor NOx (180 μg m-3) was found to be influenced by outdoor NOx (mean concentration 220 μg m-3). High I/O NO2 (ratio, R > 0.74) concentration were observed during week days and at the weekend. Mean concentrations I/O were highly correlated throughout the day and night (p < 0.01) and it is estimated that about 84% (day) and 95% (night) outdoor NOx transgressed indoors. In contrast, a different pattern of diurnal variation profiles were observed in the naturally ventilated school building (suburban). Indoor NOx concentration was dominated by an indoor NO source. Particulate concentration of indoor PM10 & PM2.5 was observed to be higher than outdoor concentrations, especially during occupied periods. The I/O PM ratios were found to differ significantly (p-value <0.05) between weekdays and weekend for fractionated PM10 & PM2.5. During weekdays only 6.8, 2.3 & 2.8% variation in the indoor concentration of PM10, PM2.5 & PM1 could be attributed to the outdoor concentration respectively. The low values of R2 revealed the independent sources of particulate matter in the indoor environment at the classroom. Conclusion: These monitoring results have revealed a number of important building design and occupancy issues that affect indoor air quality.